Former World No.1 Tiger Woods continued to exceed expectations on his latest eagerly anticipated injury comeback in the Hero World Challenge.

Woods added a second round of 68 to his opening 69 for a halfway total of seven under par, five shots adrift of surprise leader Charley Hoffman.

But the bare figures did not tell the full story of a round which featured four birdies, a spectacular eagle and signs that Woods has quickly found a solution to the chipping woes which resurfaced on Thursday.

Woods has started just three events since August 2015 and withdrew from his most recent tournament in February in Dubai after an opening 77.

The 14-time Major winner subsequently underwent spinal fusion surgery in April, his fourth back operation in the space of three years, and began a 40-1 outsider in the 18-man field.

Those odds looked somewhat generous after the first round and appeared faintly ridiculous after Woods birdied three of his first four holes on day two and eagled the ninth in spectacular fashion to claim the outright lead.

Woods holed from five feet on the first, two-putted the par-five third and converted from four feet on the fourth, but saved the best till last on the front nine on the par-five ninth.

The 41-year-old had bogeyed the same hole on Thursday after a duffed chip but this time hit a towering three-wood from 270 yards to 15 feet and then coolly rolled in the eagle putt.

Woods also birdied the 11th after a superb chip from a tight lie right of the green, but three-putted the next to drop his first shot of the day and also three-putted the par-five 15th for par.

A wayward drive on the 18th led to a closing bogey and a disappointed Woods said: "After that 31 on the front nine I could have got more on the back nine.

"I had a difficult time all day with my speed on the greens -they seemed to be about a foot faster. They were dry, they were rolling out and I airmailed a few of them well past the hole. I really did struggle with my speed.

"(But) I proved that the surgery was successful, the rehab has been fantastic and now I've got a chance to go out there and play competitive golf again."

Asked how close he is to getting back to his best, Woods added: "I'm just getting back. I've still got a long way to go. That's going to take time, a lot more practice, a lot more training and more tournaments."

Hoffman birdied the last five holes, and 12 in total, in a remarkable 63 to claim a three-shot lead over Open champion Jordan Spieth and first-round leader Tommy Fleetwood.

Fleetwood's challenge was in danger of being derailed when he double-bogeyed the 10th and dropped another shot on the 11th, but the European No.1 rallied with a hat-trick of birdies from the 13th to card a 69.

Olympic champion Justin Rose, meanwhile, was four shots off the pace after a second successive 68.